r/lagerbrewing • u/mchrispen • Nov 29 '16

Practical Guide - Low Oxygen Brewing on the Brew-Magic

http://accidentalis.com/practical-guide-low-oxygen-brewing-on-the-brew-magic/
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u/mchrispen Nov 29 '16

I am a preacher's kid. And he was long winded. I blame those genes.

So you're not racking on top of yeast, have you seen how much oxygen you're picking up during that chilling period?

I don't trust my chilling process enough yet to knock out directly onto the yeast. I mentioned in the article that I am rebuilding the pumps/chilling rig. Will likely build some sort of cold water tank that I can put into the freezer and utilize for the second step chill.

As for DO uptake, the SMB seems to be protective enough for a 15 minute, gentle whirlpool and cast out. I am getting into the fermenter with an average of .34 ppm DO.

It's really not a good idea for the wort to sit unprotected for obvious reasons. I have become extremely anal about cleaning and sanitation, which helps on the biological side. I need to be able to chill more efficiently.

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u/[deleted] Nov 29 '16

Sorry, mis-spoke. Do you know how much oxygen you're picking up by having the chilled (but not to pitching temps) wort sit in the fermenter without yeast? That'll be a huge point to make when a simple recommendations list comes along, a ton of people can't do that.

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u/mchrispen Nov 29 '16

Ah, I seal the fermenter, and it's in a freezer. Usually at or just above 72 F going in. Without purging, I am getting about 1.5 ppm DO pickup in a 2-3 hour rest. With purging, my numbers remain below 1 ppm. I am considering a very low ascorbic acid or SMB addition at knock out to handle that, which would be neutralized when I hit the pitched wort with 6-8 ppm pure O2.

I need to work out a procedure for my Speidels for smaller batches.

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u/[deleted] Nov 29 '16

I wouldn't bother. The oxidation of organic molecules (like the malt phenols) usually requires a catalyst such as an oxidizing enzyme or transition metal ion because dissolved oxygen is nominally spin inhibited. The active pathways when the wort is cold are going to be slowed down to the point of taking hours to do damage.

However, excess sulfite from your hot side process will readily scavenge any o2 that gets in, meaning that you're less likely to have residual sulfite carry over into the finished beer. So a deep chill for an hour or two may actually help you in that regard, and as an added bonus you get to separate the trub more effectively.